what is 3/5 x 12?
So we shall do this like
$$\frac{3}{5} * 12$$ $$$ Becoz we can not reduce 5 and 12 we shall simple multiply it all and then divide $$$$$
= 36/5
$$$ now i hope you can do the division yourself! No more energy saving! LOL! $$$
$${\frac{{\mathtt{3}}}{{\mathtt{5}}}}{\mathtt{\,\times\,}}{\mathtt{12}} = {\frac{{\mathtt{36}}}{{\mathtt{5}}}} = {\mathtt{7.2}}$$
3*12=36
5*1=5
36/5=7 1/5